Haobo Yu, Zimo Li, Yeyin Xia, Yameng Qi, Yingchao Li, Qiaoping Liu and Changfeng Chen
This paper aims to investigate the anti-biocorrosion performance and mechanism of the Cu-bearing carbon steel in the environment containing sulfate-reducing bacterial (SRB).
Abstract
Purpose
This paper aims to investigate the anti-biocorrosion performance and mechanism of the Cu-bearing carbon steel in the environment containing sulfate-reducing bacterial (SRB).
Design/methodology/approach
The biocorrosion behavior of specimens with Cu concentration of 0 Wt.%, 0.1 Wt.%, 0.3 Wt.% and 0.6 Wt.% were investigated by immersion test in SRB solution. By examining the prepared cross-section of the biofilm using focused ion beam microscopy, SRB distribution, bacterial morphology, biofilm structure and composition were determined. The ion selectivity of the biofilm was also obtained by membrane potential measurement. Moreover, the anti-biocorrosion performance of the Cu-bearing carbon steel pipeline was tested in a shale gas field in Chongqing, China.
Findings
Both the results of the laboratory test and shale gas field test indicate that Cu-bearing carbon steel possesses obvious resistance to microbiologically influenced corrosion (MIC). The SRB, corrosion rate and pitting depth decreased dramatically with Cu concentration in the substrate. The local acidification caused by hydrolyze of ferric ion coming from SRB metabolism and furtherly aggravated by anion selectivity biofilm promoted the pitting corrosion. Anti-biocorrosion of Cu-bearing carbon steel was attributed to the accumulation of Cu compounds in the biofilm and the weaker anion selectivity of the biofilm. This research results provide an approach to the development of economical antibacterial metallic material.
Originality/value
MIC occurs extensively and has become one of the most frequent reasons for corrosion-induced failure in the oil and gas industry. In this study, Cu-bearing carbon steel was obtained by Cu addition in carbon steel and possessed excellent anti-biocorrosion property both in the laboratory and shale gas field. This study provides an approach to the development of an economical antibacterial carbon steel pipeline to resist MIC.
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Yekun Xu, Yameng Zhang and Jiayu Zhao
This study aims to investigate whether and how the executive military experience influences accrual-based earnings management and real earnings management.
Abstract
Purpose
This study aims to investigate whether and how the executive military experience influences accrual-based earnings management and real earnings management.
Design/methodology/approach
Based on a sample of 4,392 listed firms in China between 2006 and 2022, this study examines the theoretical hypotheses by performing multiple regressions with fixed effects and a battery of robustness tests.
Findings
With a focus on executives’ decisions on the choice between two earning management methods, this paper find military executives reduce accrual-based earnings management but increase real earnings management. The mechanism of risk-aversion is verified in the post hoc analysis.
Originality/value
Most studies argue that military experience, which represents a strong sense of duty and self-discipline, can help to reduce corporate unethical behaviors. The study extends the existing literature on executives’ military experience by identifying risk-aversion rather than ethical values as the potential mechanism through which executives’ military experience affects earnings management.